1. Field of the Invention
The present invention relates to a laser cathode ray tube (laser-CRT) and a method of manufacturing the same, and more particularly, to a laser-CRT in which the structure connecting a disk to a metal ring is improved to maintain a vacuum during operation of the laser-CRT at a low temperature.
2. Description of the Related Art
Referring to FIG. 1, a conventional laser-CRT includes a glass bulb 12 having an electron gun 11 emitting electron beams inserted therein, a connection ring 13 connected to an end of the glass bulb 12, a target portion 14 on which electron beams emitted from the electron gun 11 collide to generate a laser beam to form an image, and a support ring 15 in which the target portion 14 is installed, connected to the connection ring 13. Here, the target portion 14 includes a single-crystal 16 for generating a laser beam when the electron beam is input, a resonator 18 composed of mirrors 17a and 17b formed on both sides of the single-crystal 16, and a disk 19 connected to one side of the resonator 18.
The inside of the laser-CRT is maintained in a vacuum, and when the electron beams emitted from the electron gun 11 are accelerated toward the target portion 14 to collide against the single-crystal 16 of the resonator 18, the laser beams are generated, to thereby form an image. The temperature of the single-crystal 16 must be maintained at 80-200K to generate stable laser beams, so that the disk 19 formed of sapphire having excellent thermal emission is connected to one side of the resonator 18. Also, a refrigerant such as liquid nitrogen is supplied to the disk 19 to maintain the resonator 18 at a relatively low temperature.
The room temperature of the laser-CRT becomes a low temperature during driving, so that junction portions of components are deformed due to a difference in the respective thermal expansion coefficients and thus the vacuum state of the laser-CRT may be compromised, which occurs more severely at the junction portion between the disk 19 of the target portion 14 and the support ring 15. In detail, referring to FIG. 2, the junction between the disk 19 of a nonmetal and the support ring 15, is realized by a metalizing method in which a metal layer 21 containing Mo or Mn and a Cu-layer 22 are interposed therebetween. That is, in the above junction process, a paste having Mo and Mn as a main material is coated on a surface of the disk 19 and then the surface is dried to thereby form a metal layer 21. Subsequently, when the metal layer 21 is heat-treated at a high temperature, a glass component of the disk 19 reacts with Mn of the metal layer 21 to realize a junction between the metal layer 21 and the disk 19. Also, a Cu-layer 22 is formed between the metal layer 21 and the support ring 15 using a Cu welding material, to thereby connect the disk 19 to the support ring 15.
However, when the conventional laser-CRT having the above junction structure is driven at 80.about.200K for an extended period of time, the metal layer 21 and the Cu-layer 22 tend to be brittle, so that cracks or deformations occur at the junction portion between the support ring 15 and the disk 19, to thereby damage the vacuum state of the laser-CRT.
When an impurity flows into the laser-CRT due to the lack of integrity in the vacuum state, a proceeding path of electron beams is distorted, so that the electron beams cannot accurately land, to thereby deteriorate the screen quality. Also, the durability of the laser CRT is deteriorated due to weakening of the junction portion, to thereby reduce the life of the device.